Flexible guidewire

Abstract

A guidewire suited for inserting both diagnostic and therapeutic catheters. The guidewire has an initial uniform diameter segment that is coated with Telfon along a majority of its length. This core station tapers along a uniform portion to a second constant diameter segment surrounded by a flexible spring tip. The core again tapers in a region where the flexible spring separates from the core. The core is then flattened to increase flexibility within the flexible spring and the flattened core and spring are brazed together at a extreme distal tip portion to form a hemispherical distal guidewire tip.

We claim: 
     
       1. An elongated flexible guidewire for positioning within a patient comprising: (a) a flexible wire core having a first diameter portion extending from a proximal end to a distal region of the guidewire and that tapers uniformly along a first tapered portion of said wire core to a second lesser diameter portion shorter than said first diameter portion and that again tapers uniformly along a second tapered portion to a flattened distal portion of said wire core;   (b) a flexible coiled wire spring that surrounds the wire core and is attached to said core along the length of the second lesser diameter portion of the flexible wire core and that separates from the core wire at a proximal portion of the second tapered portion, extends along the second tapered and flattened distal portions, and is attached to the flattened distal portion of said wire core at a distal end of the guidewire; and   (c) a plastic coating covering all but an extreme proximal portion of the first diameter portion of said wire core.   
     
     
       2. The guidewire of claim 1 where the coiled spring is attached to said flattened distal portion of said wire core with a brazing material which forms a rounded distal tip of the guidewire. 
     
     
       3. The guidewire of claim 1 where a portion of the coiled wire spring attached to the second lesser diameter portion of the core is closely packed with adjacent coils touching and a portion of the coiled wire spring that overlies the second tapered and flattened distal portions is wound with gaps between adjacent coils. 
     
     
       4. The guidewire of claim 1 where the coiled wire spring has a relatively uniform diameter from the region attached to the lesser diameter core wire to the portion attached to the distal end of the flattened distal portion.